Michael Thomas Barton, an inmate who suffered from mental illness and contracted the flu, died in custody because prison nurses and doctors failed to give him appropriate medical care, an advocacy group alleges in a new report released Monday.

Barton begged to stay in the infirmary of the Oregon State Penitentiary, but medical staff disregarded his pleas as well as the pleas of other inmates and prison employees to get him help, Disability Rights Oregon claims.

His health deteriorated over the last two weeks of his life as he remained bedridden in his cell, his food trays piling up on the floor because he stopped eating, the report said.

Other inmates and staff reported that Barton could barely lift his head to drink water and was pale and shivering under a blanket.

Barton had bipolar disorder and signs of dementia, the group said. In January 2018, he had symptoms of a viral illness consistent with the flu. During the remainder of the month, he was taken to the infirmary in a wheelchair pushed by other inmates multiple times. On many of those visits, he begged to be admitted to the infirmary but wasn’t, according to Disability Rights Oregon’s report.

Despite concerns expressed by the inmates and staff, nurses didn’t enter his cell to take his vital signs until Feb. 5, 2018, when he lost consciousness as he was being pushed in a wheelchair to the prison infirmary, according to Disability Rights Oregon.

Barton, 54, of Medford, died the next night at a Salem hospital from organ failure resulting from a massive staph infection, the report said.

Disability Rights Oregon investigated Barton’s death after a prison employee and other inmates alerted the group that they were haunted by Barton’s death.

The advocacy group, which represents vulnerable populations and has pushed for prison reforms for people with mental illness, conducted its own investigation, reviewed state prison reports and spoke to at least five eyewitnesses.

Nurses were indifferent to Barton’s suffering, and responded to him as if he were faking his symptoms, the report alleges.

“A man lost his life because he had a disability that resulted in very poor medical care,’’ said Joel Greenberg, an attorney with Disability Rights Oregon. “The institution failed him. … There will be other Michael Bartons unless (Oregon Department of Corrections) changes a culture that permits its staff to see patients with cognitive and mental health disabilities as less than human.’’

The advocacy group urged the Corrections Department to hire an independent prison health expert to review the state inquiry into Barton’s death, identify factors that contributed to it and recommend changes to policies or practices.

In a letter responding to the report, state Corrections Director Colette S. Peters said she disagreed with the findings, citing inaccuracies and omissions, critical of the group’s partial reliance on five inmates and non-medical prison staff.

She also criticized the advocacy group for including information from the state agency’s own peer reviews of the case, saying making the information public could chill candid self-review.

“We do not believe that a fair review and understanding of the facts and circumstances supports the conclusion that ODOC was negligent,’’ she wrote.

Peters also wrote, “We know and understand that Mr. Barton’s death has profoundly and personally concerned and affected several of his peers and neighbors, as well as ODOC staff. At ODOC we are committed to critical examination and review of the care, treatment and services we provide to the adults in our custody.’’

A state prisons doctor attributed Barton’s death to a “system failure’’ and cited significant shortcomings in his care but didn’t find negligence, according to Disability Rights Oregon. Another state corrections report acknowledged that staff didn’t recognize Barton’s critical illness.

Barton was in prison serving a nearly six-year term for second-degree robbery. He was sentenced on April 19, 2017 in Jackson County Circuit Court.

He was being held in a specialized unit called Intermediate Care Housing, reserved for people with mental illness or intellectual disabilities.

He was prescribed an antibiotic in late January 2018 due to a viral illness. But nurses and medical staff at the prison “repeatedly misinterpreted’’ Barton’s “obvious inability to understand’’ or follow their instructions, such as the need to drink fluids, as “malingering and/or refusal to take medication,’’ the report said.

Just days before his death, a corrections employee called the infirmary to ask that Barton be readmitted immediately because his declining health. A nurse responded that he “just needs to rest,’’ according to the group’s report.

The employee, unnamed in the report, told Disability Rights Oregon that much of the corrections and nursing staff assumed Barton was “just complaining and being melodramatic,’’ the report said.

No autopsy was done. But the Corrections Department’s chief medical officer, Dr. Reed Paulson, concluded that Barton’s death was the result of Influenza B, leading to MRSA pneumonia, sepsis, severe septic shock and cardiopulmonary arrests and a “multisystem failure’’ with severe anoxic brain injury, according to Disability Rights Oregon.

Paulson found that Barton’s visits with multiple staff and abnormal vital signs after diagnosis of pneumonia “represented opportunities for more earlier intervention” that could have prevented his death, including sending him back to the infirmary, according to Disability Rights Oregon’s examination of the doctor’s review.

But Paulson also noted the prison infirmary is “extremely ill-constructed’’ for admitting flu patients because it has many medically fragile patients or those with compromised immune systems. “This creates an understandable hesitation in staff,’’ Paulson wrote.

In the mortality review, Paulson rated several aspects of Barton’s medical treatment as possibly not meeting the community standard of care: staff response, level of housing/care appropriate, preventive measures, diagnosis timely and accurate diagnosis.

The doctor recommended the prison increase nurse and physician staffing.

“It is clearly demonstrated in this case that the fault does not lie in one person’s mistake, but rather highlights system failure that has affected many staff.’’

Barton’s family learned of his death through a friend’s Facebook posting that said, “Michael Barton RIP.” They didn’t learn the circumstances or cause of his death until Disability Rights Oregon contacted them in June, more than a year after Barton’s passing.